I've had a few. Generally it ends up being more: Take the feat, give a GM an idea of the type of cohort you'd like, gain a Party-NPC shortly down the road who likes your character[and doesn't take a cut of the XP but still gains some].

This means the GM makes the character, and if you've got good communication with them you can get something close to what you wanted. It adds roleplay potential, and generally makes GMs hate the feat less. It does however mean you have to treat them like a person and not an extension of yourself that you can exploit more easily.

Now Followers... that's a whole different story. Generally my group doesn't really bother with them much, just because it's typically highly mobile campaigns and we don't want a horde of 20+ super weak NPCs following us into situations where a single AoE is going to wipe out a ton of people whose contributions to combat are generally negligible. They do come into play a bit more if there's any sort of base of operations.

Edit: Although now that I think about it, I did once use followers as crew for my Airship. That worked out rather well to be honest.

Leadership got banned from the table I play at, I may have made a wizard who was teleportation based and had all item creation feats. I miss that paladin, the gm killed him viciously and then banned Leadership.

Oh hey, in Pathfinder, they fixed the exploit where, technically, your strongest followers could get the leadership feat too. In 3.5, you could get leadership at level 6, and the highest-level followers you could get were level 6, so if you gave leadership to all of your 6th-level followers and cohorts, and to all their 6th-level followers and cohorts, and so on, you could end up with an army of about 1,500.

So, for the price of one feat and some stat boosters, you could literally command the entire population of a small town. The only saving grace is that the DM has enough control to prevent the idea from happening, meaning that this trick only works for powerful NPCs and enemies while being completely unavailable to players... oops, did I save "the only saving grace?" Sorry, I meant, "the only thing that makes this worse."

It's amazing what changing a level requirement by 1 can do for game balance.

It's not that impossible. A 1st-level character with the right magic items can have a charisma of 29 (+9), and that increases by 1 at every level that's a multiple of 4. Then there's the fact that your leadership score gets modified by all kinds of factors. You could have a maxed out leadership score at ridiculously low levels... as low as 9th level, I believe (your cohort wouldn't be quite maxed, but the level cap on them makes that irrelevant). Sure, cloaks of charisma and tomes of leadership for all your cohorts and 6th-level followers would be expensive as anything, but they also bring some of their own money as well, so it's not that bad.